Furnace structure



April 25, 1939. R. RoBlNsoN FURNACE STRUCTURE Filed octp'e, 1957 3 Sheets-Sheet l l IxllllllllllL FIG-1 NVENTOR.

April 25, 1939.

L. R. ROBINSON FURNACE STRUCTURE Filed oci. e, 1937 5 Sheets-Sheet 2 Fla-z v INVENTOR,

` 3 Sheets-Sheet 3 L. R'ROBINSON FURNACE STRUCTURE Filed Oct. 6, 1937 April 25, 1939.

Am R W M QATTORNEY.

Patented Apr. 25, 1939 UNITED STATES PATENT oFFlcE United Combustion Corporation, Cleveland,

Ohio, a corporation of Delaware Application October 6,

7 Claims.

This invention relates to furnaces for drying kilns and the like, and particularly to a furnace structure which may be converted readily from a semi-muffled type to a full muffled type.

One of the principal objects of the present invention is to provide a furnace having both a flash wall and a checker wall in combination with each other, with a flue opening thro-ugh the checker wall such that excess air may be drawn in through the flue When the usual power operating fan associated with the furnace is operated and in which the stack acts automatically to maintain a draft for sustaining combustion when the fan is stopped.

Another object is to provide a furnace of this character in which the heat which is normally lost from the top wall of the furnace may b recuperated and used.

An equally important object is to provide a furnace and tunnel combination in which the furnaces and tunnels are arranged so that any number of furnaces may be disposed in a single bank, all in communication with a common final discharge tunnel, and so that each supplies its full proportion of the required heat.

Still another object is to provide a furnace for drying kilns which may be converted readily into a muffled or a semi-muffled type, whereb-y it may be adapted to different uses.

Other objects and advantages will become apparent from the following specification, wherein reference is made to the drawings, in which:

Fig. 1 is a front elevation of a furnace and tunnel structure embodying the principles of the present invention, part thereof being shown in section for clearness in illustration, and the sections being taken on the planes indicated by the lines ISL-Ia and Ib-Ib, respectively, in Fig. 2.

Fig. 2 is a cross sectional view taken on a plane indicated by the line 2--2 in Fig. 1;

Fig. 3 is a diagrammatic horizontal sectional view showing the connections between the bank of furnaces and the tunnels; and

Fig. 4 is a diagrammatic fragmentary sectional view of a portion of the furnace illustrating the manner in which the air passages around the stack are arranged.

Referring to the drawings, the furnace shown for purposes of illustration comprises a single bank of three furnace units similar to the lefthand unit shown in front elevation in Fig. 1. Each furnace unit comprises a firing compartment or chamber I of a well known construction and having a firing passage 2 and an ash-removal passage 3, and inasmuch as all are the 1937, Serial No. 167,544

chamber, indicated generally at 6, is substanl tially coextensive transversely of the furnace unit with the firing chamber I. Both chambers I and b are closed at thetop by a suitable common arch wall 'l Which extends fore and aft of the furnace unit. The chamber 6 is provided with a rear end or partition wall 8 which is in spaced relation both to theI flash wall 4 and to a rear wall 9 of the furnace structure.

Between the partition wall 8 and the ash wall 4 is arranged an upright stack I0 which extends from the bottom'of the chamber 6 upwardly through the wall I and the top of the furnace structure, as illustrated, and which iscoextensive in Width with the chamber 6 at that portion of the stack within the chamber 6. The stack I0 has an arched opening II in the face toward the flash wall 4, through which the products from the front of the chamber 6 may enter the stack. The front wall I2 of that portion of the stack exposed Within the chamber 6 is in the form of a checker wall, or brick grillw'ork, such that products of combustion iiowing over the flash Wall 4 may pass both through the arch Il into the stack and through checker passages I3 of the wall I2 intoI the stack. In addition, the opposite or rear Wall of the stack is in the form of a checker wall having passages I4 such that products may pass directly Vthrough the stack from within the stack into the rear of the charnber 6.

The chamber 6, in turn, is in communication at its rear, bottom portion through a passage I5, with a transverse tunnel I6 and main discharge tunnel I'l. T'he usual fan (not shown) is provided for drawing air and products from the main discharge tunnel Il and for forcing the air and products to points of application.

Spaced above the top or arch wall 'l is a supplemental or recuperating arch wall 20 which ter illustrated in the right end portion of Fig. 2, lateral or transversely spaced arches 26 are arranged adjacent the stack I and bridge between adjacent recuperating walls 20 and dening with the arch walls 2U, passages 21 which conduct air from between the arch walls l and 20 around the stack to the rear thereof. The passages 21 are substantially equal in capacity to the space or passage 24. Thus the air, when reaching the stack I El, flows, as indicated by the arrows 25, laterally thereof, through the passages 21 which afford communication between the space beneath the recuperating arch wall 20 and the arch wall 1. The passages defined by the recuperating arch walls 20 and the laterally spaced arches 26 open between the rear end wall 8 of the compartment and the rear wall 9 of the unit into the passage 28, whereupon they flow downwardly between the walls 8 and 9 and out through the archway 29 into the lower portion of the chamber 6 and tunnel i6.

The ends of the arches 26 rest on supplemental arches 30 at the adjacent ends of the arches 2B. The arches 30 define, with the top arch wall 1 of adjacent furnace units and the side walls thereof, passages 3l through which air may pass around the side walls of the chambers 6 and into the passages between the walls 8 and 9. Thus the entire outer wall structure of the firing chamber I and chamber 6 are bathed in fresh outside air which is heated by recuperation of heat from the side walls and top wall of the furnace. For purposes of illustration, a bank of three furnaces has been shown, and since the furnaces are the same in structure, the left-hand furnace in Fig. 2 only has been described.

It is apparent that when the fan is operating to draw air and products from the tunnel II, air is drawn thereby through the ring compartment I over the flash wall, through the arch II at the bottom of the stack, and through the rear wall of the stack and downwardly through the passage I5. At the same time, air is drawn around the outside of the furnace and finally through the passage 29 at the base of the wall 1, and the passage I5. Concurrently, since the stack is in the form of a checker, excess air will be drawn in through the stack. If, however, the fan is stopped, the ow of air changes so that the stack becomes operative for maintaining a draft through the chamber I, thereby sustaining the fire.

If it is desired to convert the furnace to a full muiiied type, it is only necessary to plug up the passages I3 and I4 in the stack, in which instance all of the heat will be obtained by radiation through the walls of the furnace, and the surrounding air streams will then provide the sole heated media.

Referring next to Fig. 3, it will be noted that the furnace unit above described is at the central portion of the transverse tunnel I6 which is the same part of the tunnel I6 at which the tunnel II is connected thereto. Consequently, air discharged from the passage I may ow comparatively directly to the tunnel I1. The other furnace units, however, are spaced laterally from the entrance of the tunnel I1. The other units are provided with passages 46, respectively, which correspond in function to the passage I5. Since the heated products discharged from the passage 40 must turn at right angles to its original direction when it enters the tunnel I6 and then turn again from the tunnel I6 to the tunnel Il, considerable flow loss is occasioned.

In order to make possible an equal amount of heating by each furnace unit in the bank, each of the passages 40 is larger than the passage I5. If additional furnace units are added and positioned outwardly from the furnaces having the passages 40 and thus farther from the tunnel I1, their discharge passages into the tunnel I6 must be larger than the passages 40. The passage I5 therefore must be less than either of the two adjacent passages 40, and the passages 40 in turn must be less than any next successive outwardly disposed passages of corresponding furnace units. Likewise, the tunnel I 'I must be equal to or greater in capacity than the sum of the capacities of the passages I5 and 40. Likewise, the tunnel I'I must be greater in area than the tunnel I6. Due to this difference in areas and capacity of the tunnels and passages, each furnace unit supplies substantially the same amount of heated products or heated fresh air in case the furnace is operated as a muille type.

By virtue of the structure above described, it is apparent that heat is recuperated from the top of the top arch wall of the furnace, where usually the greatest loss of heat occurs and where, heretofore, it was considered impractical to recuperate heat. The draft on all three furnaces is equalized. Further, it is possible to provide passages around the stack which in area are equal to or greater than the area of the stack exposed toward the air flowing over the wall 1. The furnace is readily adapted for drying by products of combustion when operated as a semi-muffled furnace, secondary combustion being obtained because of the secondary pre-heated air supplied. When it is desired to eliminate the products of combustion in the drying kiln, it is only necessary to muifle the furnace by merely laying brick in the openings I3 and I4. When the furnace is used as a semi-muffled type, the rate of combustion may be controlled by the fan.

Having thus described my invention, I claim:

1. A furnace structure comprising enclosing walls defining a forward ring chamber and a rearward combustion chamber, a flash wall extending upwardly from the bottom of the firing chamber and coextensive therewith transversely and terminating in spaced relation tc the top wall of the firing chamber and separating the firing chamber from the combustion chamber except over the top of said flash wall, a stack in and spaced from the forward and rear ends of the combustion chamber and substantially coextensive therewith transversely and having an opening in one of its walls which faces toward the flash wall, said opening being placed near the bottom of said combustion chamber, said combustion chamber having a passage affording an exit for products of combustion from said combustion chamber at a point beyond the stack in a direction away from the flash wall, and the front and rear walls of said stack being in the form of checkers and having passages for products of combustion from the fore portion of the combustion chamber through the stack walls to the rear portion thereof.

2. A furnace structure comprising a plurality of furnace units, each unit having side walls and a top wall and the units `being arranged in a row, side by side, with adjacent side walls spaced from each other and affording passages for air between the units, recuperating walls for the units and spaced above the top walls thereof, respectively, passages for air between the top wall and the recuperating wall, all of said passages being open at the front of the furnace structure, means associated with the furnace units respectively and having passages respective to the units and connected with the foregoing passages of their associated units for receiving air from around the side and top walls of their associated units and having a discharge opening for discharging air therefrom.

` 3. A furnace structure comprising top, side, end and front walls defining a compartment, a fiash wall in the compartment extending from the bottom thereof upwardly and terminating in spaced relation to the top wall thereof, said iiash Wall being spaced from the front wall and from the rear wall and defining therewith and with the side walls a forward firing chamber and a rearward combustion chamber which communicates with the firing chamber above the flash wall, the

bottom of the combustion chamber being below the level of the bottom of the firing chamber, a stack extending from the bottom of the combustion chamber upwardly to and through the top wall thereof and being substantially coextensive transversely with the combustion chamber and spaced rearwardly from the flash wall and forwardly from said rear wall, said combustion chamber having a discharge opening at the bottom thereof between the stack and rear wall, and said stack having an opening at the bottom of its forwardly exposed wall connected with the combustion chamber and the front and rear walls of the stack being in the form of a checker.

4. In a furnace structure, a plurality of furnace units having side and end walls, said units being arranged in a row with the side walls spaced from each other, each furnace unit having an arched top wall, a stack for each unit extending through and above the top wall thereof, arched recuperating walls in spaced relation above the top walls of the units and defining air passages over said top walls from the front of the furnace unit to the stack, supplemental arch Walls bridging between the top walls and across the space between adjacent side walls of the units and supporting adjacent ends of the recuperating arch walls, transversely spaced arch walls supported on the recuperating arch walls and bridging therebetween and extending from a point forwardly of the stack to the rear thereof, the spaces between the transversely spaced arch walls and recuperating arch walls being in communication respectively with the spaces between the recuperating arch walls and top walls, and means at the rear of the furnace structure and having a passage in communication with the space between the side walls of the unit and with the space between the transversely spaced arch walls and the recuperating arch Walls.

5. A furnace structure comprising a top wall and enclosing side and end walls defining a front firing chamber and a rear combustion chamber in communication with the firing chamber, a stack Within and spaced from the front and rear of the combustion chamber and substantially coextensive therewith transversely extending above the top wall and having an opening in one of its walls in communication with the combustion chamber, said combustion chamber having a discharge opening rearwardly from the stack and affording an exit for products of combustion from said combustion chamber, the front and rear Walls of said stack being in the form of checkers and affording passage for products of combustion from the fore part of the combustion chamber directly through the stack to the rear portion thereof, said chambers having a common top wall in the form of an arch, a recuperating arch wall spaced above said arch and defining therewith a passage which is open at the front of the furnace, a rear wall for the furnace and spaced from the said rear end wall and defining therewith a passage which communicates with said discharge opening, and means defining with said recuperating arch wall passages around the portion of the stack which is above the top wall in communication with the space between said rear wall and rear end wall. l

6. A furnace structure comprising a plurality of furnace units, each unit having side walls and a top wall, the units being arranged in a row side by side, with adjacent side walls spaced from each other and affording passages for air between the units, recuperating walls for the units and spaced above the top walls thereof respectively and defining passages for air between the top walls and the recuperating walls, all of said passages being open at the front of the furnace structure, means associated with the furnace units respectively and having passages connected with the foregoing passages of their associated units for receiving air from around the side and top walls of their associated units and having a discharge opening for discharging air therefrom, a transverse tunnel extending lengthwise of the row of furnace units and in communication with said openings of the units adjacent to the units, respectively, a main tunnel extending at right angles to the transverse tunnel substantially midway between the ends of the row of units, the opening of the furnace unit nearest the main tunnel being smaller than the opening of each of the next adjacent units and the main tunnel being larger than the transverse tunnel.

7. A furnace structure comprising top, side, rear and front walls defining a compartment, a flash `wall in the compartment extending from the bottom thereof upwardly and terminating in spaced relation to the top wall thereof, said flash Wall being spaced from the front wall and from the rear Wall and defining therewith and with the side walls a forward firing chamber and a rear combustion chamber which communicates with the firing chamber above the flash wall, a stack extending from the bottom of the combustion chamber upwardly to and through the top wall thereof and being substantially coextensive transversely with the combustion chamber and spaced rearwardly from the flash wall and 'forwardly from the said rear wall, said combustion chamber having a discharge opening at the bottom thereof between the stack and rear wall, said stack having an opening at the bottom of its front wall and connected with the combustion chamber, the front and rear walls of the stack being in the form of a checker, walls defining, with the walls of the comp-artment, passages for air around the outside of the compartment walls, a rear end wall for the combustion chamber spaced rearwardly from the stack and forwardly of the rear wall of the furnace unit and defining with said rear wall, a passage which is in communication with the passages around the outside of the compartment, and said rear end wall having a passage near the bottom connecting the combustion chamber with the space between said rear wall and rear end Wall.

LAWRENCE R. ROBINSON. 

